I've got both Profilers and I3's... I choose to use the I3s
Profilers are quick to switch the lenses, but I prefer the I3's on my face.
So to avoid the problems with switching lenses in a timely manner, I bought additional lenses and the foam surrounds. I can swap them over more quickly should the need arise. Though this does increase the cost of owning I3s.
I also wear glasses, so face twice the chance of fogging. The option for the I3 fan swung it for me, though I know some people like the fan even if they don't wear glasses.
The fan makes a small buzz, and the first time I wore it I though there was something wrong with my marker
I've found the profilers generally don't fog unless it's really warm during a longer games, or when raining while playing. But again wearing glasses doesn't help!
But it's all down to personal choice, try before you buy is the best advice!